Use of GM to produce sterile male insects

Scientists at a British company have been able to genetically modify the Diamondback moth, one of the world’s most damaging agricultural pests, so that reproduction is reduced drastically.

Oxitec is a company pioneering an approach to combat insects that spread disease and damage crops by creating sterile male insects to mate with females of the same species, resulting in a population decline.

The Diamondback moth is a global pest that attacks many crops including brassica crops such as cabbages and cauliflowers. It is estimated to cost farmers $1billion annually to control. There is no global estimate to the total value of crops destroyed.

As the company noted, rising global food demand, environmental concerns and insecticide resistance are leading to pressure to find new ways to combat insects that reduce crop yield and quality.

Conventional pest control in agriculture rests heavily upon the use of chemical pesticides which are sprayed directly onto the food crop. While effective against the target insect, insecticides can also have a harmful effect on non-target insects and environmental concerns have driven the search for less toxic and persistent chemicals. As chemicals have been withdrawn, the reliance on fewer products has exacerbated the problem of pesticide resistance in the target insect.

Agricultural research has also led to the development of genetic modification techniques whereby the food crop is modified to express a protein to kill feeding insects. However, in both chemical control and GM crops, the control that targets the insect is applied on, or through, the food itself.

Oxitec by using GM insects has pioneered a third way of insect control. Oxitec’s solution creates ‘sterile’ male insects that mate with wild females of the same species, and the genetic modification prevents females in the next generation from surviving to adulthood, causing a decline in the target population.

”GM technology in agriculture is normally associated with modification of the food crop and giving it a competitive advantage in terms of boosting its defense against insects” commented Neil Morrison, Ph.D., who leads the Diamondback moth project in Oxitec, ”but at Oxitec we have taken an alternative approach; we harness genetics to provide the effect we want without making any permanent change to the species and without the gene persisting in the environment. So rather than use a recombinant DNA approach to give the crop a competitive advantage we give the insect itself a distinct disadvantage, i.e. the inability to reproduce. Moreover, the modification is self-limiting as it relies on the concept of sterility, so is finite—it does not persist in the environment. This provides the potential for a safe and sustainable form of insect control.”

Morrison added, ”Transforming the pest, as we are reporting here, is only the first phase. What will follow is a careful step-by-step process in development, evaluation and consultation. However brassicas are a hugely important food all over the world and the potential to provide a new safe and environmentally friendly form of insect control is very exciting."